Influence of shaft length on torsional behavior of endodontic nickel-titanium instruments.

Torsional stresses are one of the most frequent causes of intracanal separation of nickel-titanium endodontic instruments, which represents a great concern of endodontists. For this reason, torsional resistance of rotary instruments has been deeply investigated by determining all parameters that can influenced it, that can be summarized in: (1) Tooth-related factors, (2) Strategy-related factors and (3) Instrument-related factors. This study was conducted to examine the influence of shaft length on torsional resistance of a nickel-titanium rotary instrument and if it should be considered as an Instrument-related factor. With this aim, 120 Twisted Files Adaptive M-L (TFA M-L) NiTi instruments (SybronEndo, Orange, CA, USA) were divided into 6 experimental groups (n = 20), according to instruments length and size: Group 1, 20 TFA M-L1 25/08 23 mm; Group 2, 20 TFA M-L1 25/08 27 mm; Group 3, 20 TFA M-L2 35/06 23 mm; Group 4, 20 TFA M-L2 35/06 27 mm; Group 5, 20 TFA M-L3 50/04 23 mm; and Group 6, 20 TFA M-L3 50/04 27 mm. All instruments were submitted to a static torsional test, blocking each instrument at 3 mm from the tip and rotating it until its fracture. Torque to Fracture (TtF) and fragments length were registered and all data were statistically analyzed. Results showed that Groups 2, 4 and 6 had a higher TtF, respectively, than Groups 1, 3 and 5, which differ from the former just for shaft length. Group 6 showed the highest torsional resistance (1.31 ± 0.08 Ncm), whilst Group 1 the lowest (0.40 ± 0.08 Ncm). According to that, it can be stated that the longer the instrument, the higher the torsional resistance is, proving that shaft length should be considered as an important factor about torsional resistance.

How to Improve Properties of Nickel-Titanium Rotary Instruments.

In the last decades, the use of nickel-titanium (Ni-Ti) rotary instruments has become the most effective and popular method among endodontists for shaping root canals, even if there are still concerns regarding the increased risks of intracanal breakage or weakening of the instruments.1,2 So manufacturers started to modify the cross-sectional geometrical aspects of the files in order to improve their resistance to torsional and cyclic fatigue. Design is a major feature in determining instruments' properties including cutting efficiency, removal of debris, stresses generated during instrumentation, and the relative resistance to these stresses; however, a perfect design is not existing and any change in design is likely to provide some advantages but also some disadvantages.3,4.

Possible Complications of Endodontic Treatments.

Endodontic treatments tend to have very high successful rates in spite of the fact that they are quite an invasive, difficult procedure, especially in complex anatomies. Some complications can arise during or after a root canal procedure due to poor understanding of the anatomy and iatrogenic errors mainly during instrumentation. While some of these problems can be anticipated, many can never really be predicted.1-3 As a consequence, retreatment has become a well-defined field of knowledge and expertise in endodontics, since most complications can be solved with proper surgical or nonsurgical retreatments.4 Reinfection or persistent infections: Root canal treatment can fail due to a persistent bacterial infections or reinfections. These include inadequate shaping, cleaning, and obturation procedures, poor restorations, and exposure through a fracture. The remedies are dependent on the primary cause of the reinfection and the affected parts. Persistent infection is the major cause of short-term endodontic failures.5.

Fatigue Resistance of Two Nickel-Titanium Rotary Instruments before and after Ex Vivo Root Canal Treatment.

AIM: The aim of the present study is twofold: to evaluate cyclic fatigue resistance differences of two different nickel-titanium rotary instruments, brand new and after an ex vivo instrumentation of single root extracted teeth. MATERIALS AND METHODS: Twenty new S One 20.06 were randomly divided into two groups. The first group (n = 10) was immediately subjected to a cyclic fatigue test (S One Group I). The second group (n = 10) (S one Group II) performed a cyclic fatigue test after three ex vivo root canal treatment with a single-file technique. The same process has been carried out for 20 M-Two 20.06 instruments. RESULTS: Mean time to fracture (TtF) for Group I was 51.14 ± 1.28 for S One and 32.62 ± 0.17 for M-Two 20.06 and for Group II was 46.00 ± 0.99 for S One and 27.75 ± 1.58 for M-Two 20.06. The reduction in TtF values from Group I to Group II was 11% for S One and 15% for M-Two. Statistical analysis found significant differences in all the groups examined (p value < 0.05). Mean fragment length (FL) for Group I was 3.07 ± 0.17 for S One and 3.05 ± 0.14 for M-Two 20.06 and for Group II was 3.05 ± 0.07 for S One and 3.05 ± 0.14 for M-Two 20.06. Statistical analysis was pursued, and no significant difference was found (p value > 0.05). CONCLUSION: The S-One showed significantly more resistance to cyclic fatigue stress than M-Two for both new and used instruments. This validates the hypothesis that the AF H wire enables the S One files to endure more the cyclic fatigue stresses. CLINICAL SIGNIFICANCE: This study demonstrates the cyclic fatigue resistance of a new endodontic instrument after repetitive usage.

Increasing the collection efficiency of time-correlated single-photon counting with single-photon avalanche diodes using immersion lenses.

Single-photon avalanche diodes (SPADs) achieving high timing resolution (≈20-50 ps) developed for time-correlated single-photon counting (TCSPC) generally have very small photosensitive areas (25-100 µm in diameter). This limits the achievable photon counting rate and signal-to-noise ratio and may lead to long counting times. This is detrimental in applications requiring several measurements, such as fluorescence lifetime imaging (FLIM) microscopy, which requires scanning, and time-domain diffuse optical tomography (TD-DOT). We show in this work that the use of an immersion lens directly affixed onto the photosensitive area of the SPAD helps alleviate this problem by allowing more light to be concentrated onto the detector. Following careful optical design and simulations, our experimental results show that it is actually possible to achieve the predicted theoretical increase in the photon counting rate (we achieve a factor of ≈4 here). This work is of high relevance in high timing resolution TCSPC with small photosensitive area detectors and should find widespread interest in FLIM and TD-DOT with SPADs.

Recognition of a patient with neck autonomic dysfunction: findings from a rare case report of harlequin syndrome in direct access physiotherapy.

BACKGROUND: Harlequin syndrome is a rare autonomic condition consisting of unilateral facial flushing and sweating induced by heat, emotion or physical activity. The affected side presents anhidrosis and midline facial pallor due to denervation of the sympathetic fibers. CASE DESCRIPTION: This case describes a patient who reported right-side redness of the face associated with hyperhidrosis during physical activity. She had two previous major motor vehicle accidents. The patient demonstrated difficulties in the visual accommodation of the left eye, but cranial nerve assessment was unremarkable; the patient was then referred to an ophthalmologist, who excluded any autonomic dysfunction as the primary cause of convergence and visual acuity. OUTCOMES: A left-sided sympathetic dysfunction with Harlequin sign diagnosis was made followed by a progressive compensatory adaptation of the right face. The patient was educated and reassured about the benign nature of her problem. DISCUSSION: Knowledge of the autonomic nervous system is still limited in clinical practice. Although challenging, physiotherapists should develop the knowledge and ability needed to perform appropriate assessment of autonomic dysfunctions. CONCLUSION: A dispositional reasoning model should be considered in differential diagnosis.

A guide to identify cervical autonomic dysfunctions (and associated conditions) in patients with musculoskeletal disorders in physical therapy practice.

BACKGROUND: Differential diagnosis is a hot topic in physical therapy, especially for those working in a direct access setting dealing with neck pain and its associated disorders. All international guidelines agree in recommending to first rule out non-musculoskeletal pathologies as the cause of signs and symptoms in the patient. Although the autonomic nervous system (ANS) has a crucial role and is also involved in pain conditions, coverage of it in neuroscience textbooks and educational programmes is limited and most healthcare professionals are unfamiliar with it. Although autonomic conditions are benign in nature, they are clinically of great importance as they may be a 'red flag' warning of an injury along the sympathetic pathway. Therefore, sound knowledge of the ANS system is essential for clinicians. OBJECTIVE: To develop physical therapists' knowledge of and confidence in understanding cervical ANS function and dysfunction, thus enhancing clinical reasoning skills and the pattern recognition process, and performing and interpreting objective examinations. METHODS: This master class provides an introductory guide and essential knowledge to facilitate clinicians to understand cervical autonomic dysfunctions and their clinical evaluation. The optimal referral method is also handled. CONCLUSIONS: Gaining knowledge and understanding of the ANS, its function, its dysfunction, and the related clinical manifestations is likely to lead to a decision-making process driven by 'science and conscience'. This will empower physical therapists to be aware of subtle clues that may be offered by patients during the interview and history intake leading to the appropriate physical examination and triage.

Physiotherapy Screening for Referral of a Patient with Peripheral Arterial Disease Masquerading as Sciatica: A Case Report.

Many causes potentially underline pain in the lower extremities, presenting a real challenge for primary care clinicians in the recognition of the source of the patient's complaints. Peripheral arterial disease (PAD) is defined as a total or partial blockage of the vessels that supply blood from the heart to the periphery. PAD of the lower extremities may masquerade as lumbosacral radiculopathy (LSR)-a common source of leg pain. Physiotherapists should be able to screen for PAD in people presenting with pain in the lower extremities. Failure to correctly screen for PAD could put the patient at risk of severe disability and possible permanent sequelae. This case report outlines the relevant concepts relating to the pathophysiology, screening, and differential diagnosis of PAD, and then further describes the relevant findings from the history and physical examination from the physiotherapist's perspective in a patient with an unusual symptom presentation. Although the patient was referred by a physician with a diagnosis of LSR, our case highlights the pivotal role of skilled physiotherapists in triaging a severe lower-limb PAD in need of referral. Therefore, this case report aims to increase clinicians' awareness of the clinical features of a complex case of PAD.

Identifying peripheral arterial diseases or flow limitations of the lower limb: Important aspects for cardiovascular screening for referral in physiotherapy.

Many conditions could potentially cause pain in the lower limbs. One of these is peripheral arterial disease (PAD). PAD is often a real challenge to be recognized for clinicians due to symptoms that commonly mimic musculoskeletal conditions. PAD is defined as a total or partial blockage of the vessels that supply blood from the heart to the periphery. Its prevalence is around 7 percent in subjects between 55 and 59, reaching almost 25% in individuals between 95 and 99 years old. The most dominant symptom of PAD is lower limb pain. Also, PAD can produce other symptoms such as discoloration, altered skin temperature, and, when arterial blood flow is insufficient to meet the metabolic demands of resting muscle or tissue, focal areas of ischemia. In our view, physical therapists should be capable of triaging for PAD in a direct access setting. Therefore, in this Professional Issue, we present the main characteristics of PAD and the physiotherapy role in its management. A supplementary step-by-step guide will provide further resources for testing PAD.

Correlation between Peri-Implant Marginal Bone Loss Progression and Peri-Implant Sulcular Fluid Levels of Metalloproteinase-8.

OBJECTIVES: The aim of this retrospective study was to analyze peri-implant marginal bone loss levels/rates and peri-implant sulcular fluid levels/rates of metalloproteinase-8 in three timeframes (6 months post-surgery-restoration delivery (T0)-and 6 (T6) and 24 (T24)-months post-loading) and to evaluate if there is a correlation between peri-implant sulcular fluid levels of metalloproteinase-8 and peri-implant marginal bone loss progression. MATERIALS AND METHODS: Two cohorts of patients undergoing implant surgery between January 2017 and January 2019 were selected in this retrospective study. A total of 39 patients received 39 implants with a laser-microtextured collar surface, and 41 subjects received 41 implants with a machined/smooth surface. For each patient, periapical radiographs and a software package were used to measure marginal bone loss rates. Implant fluid samples were analyzed by an enzyme-linked immunosorbent assay (ELISA) test. The modified plaque index, probing depth, and bleeding on probing were also recorded. RESULTS: High marginal bone rates at T24 were strongly associated with elevated rates between T0 and T6. The levels of metalloproteinase-8 were significantly more elevated around implants with marginal bone loss, in relation to implants without marginal bone loss. Marginal bone loss (MBL) rates at 24 months were associated with initial bone loss rates and initial levels of metalloproteinase-8. CONCLUSIONS: Peri-implant marginal bone loss progression is statistically correlated to peri-implant sulcular fluid levels of metalloproteinase-8. Moreover, the initial high levels of marginal bone loss and metalloproteinase-8 can be considered as indicators of the subsequent progression of peri-implant MBL: implants with increased marginal bone loss rates and metalloproteinase-8 levels at 6 months after loading are likely to achieve additional marginal bone loss values.

Modulation of the Dental Pulp Stem Cell Secretory Profile by Hypoxia Induction Using Cobalt Chloride.

The action of stem cells is mediated by their paracrine secretions which comprise the secretory profile. Various approaches can be used to modify the secretory profile of stem cells. Creating a hypoxic environment is one method. The present study aims to demonstrate the influence of CoCl2 in generating hypoxic conditions in a dental pulp stem cell (DPSCs) culture, and the effect of this environment on their secretory profile. DPSCs that were isolated from human permanent teeth were characterized and treated with different concentrations of CoCl2 to assess their viability by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and proliferation by a cell counting kit (CCK)-8 assay. The gene expression level of hypoxia-inducible factor 1-alpha (HIF-1α) was analyzed by quantitative real time polymerase chain reaction (qRT-PCR) to demonstrate a hypoxic environment. Comparative evaluation of the growth factors and cytokines were done by cytometric bead array. Gene expression levels of transcription factors OCT4 and SOX2 were analyzed by qRT-PCR to understand the effect of CoCl2 on stemness in DPSCs. DPSCs were positive for MSC-specific markers. Doses of CoCl2, up to 20 µM, did not negatively affect cell viability; in low doses (5 µM), it promoted cell survival. Treatment with 10 µM of CoCl2 significantly augmented the genetic expression of HIF-1α. Cells treated with 10 µM of CoCl2 showed changes in the levels of growth factors and cytokines produced. It was very evident that CoCl2 also increased the expression of OCT4 and SOX2, which is the modulation of stemness of DPSCs. A CoCl2 treatment-induced hypoxic environment modulates the secretory profile of DPSCs.

Bright nanoscale source of deterministic entangled photon pairs violating Bell's inequality.

Global, secure quantum channels will require efficient distribution of entangled photons. Long distance, low-loss interconnects can only be realized using photons as quantum information carriers. However, a quantum light source combining both high qubit fidelity and on-demand bright emission has proven elusive. Here, we show a bright photonic nanostructure generating polarization-entangled photon pairs that strongly violates Bell's inequality. A highly symmetric InAsP quantum dot generating entangled photons is encapsulated in a tapered nanowire waveguide to ensure directional emission and efficient light extraction. We collect ~200 kHz entangled photon pairs at the first lens under 80 MHz pulsed excitation, which is a 20 times enhancement as compared to a bare quantum dot without a photonic nanostructure. The performed Bell test using the Clauser-Horne-Shimony-Holt inequality reveals a clear violation (S CHSH > 2) by up to 9.3 standard deviations. By using a novel quasi-resonant excitation scheme at the wurtzite InP nanowire resonance to reduce multi-photon emission, the entanglement fidelity (F = 0.817 ± 0.002) is further enhanced without temporal post-selection, allowing for the violation of Bell's inequality in the rectilinear-circular basis by 25 standard deviations. Our results on nanowire-based quantum light sources highlight their potential application in secure data communication utilizing measurement-device-independent quantum key distribution and quantum repeater protocols.

Erratum: Bright nanoscale source of deterministic entangled photon pairs violating Bell's inequality.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Torsional Resistance of Two New Heat Treated Nickel Titanium Rotary Instruments: An in Vitro Evaluation

Abstract Objective: To evaluate the difference in torsional resistance, angular deflection and fragment length between two new rotary instruments: AF Blue S4 and S-One. These files share all features except cross-sectional design. Material and Methods: A total of 40 new Nickel-Titanium instruments of 25 mm in length were tested in this study and divided in two groups: 20 AF Blue S4, tip 25 and constant 6% taper and 20 AF-Blue S4 tip 25 and constant 6% taper. The torsional test was performed by the use of a torque recording endodontic motor (KaVo, Biberac, Germany). Torque to Fracture (TtF), Angular Deflection (AD) and Fragment Length (FL) was recorded for each instrument. To ensure an immovable block at 3mm of the instrument tip, an auto-polymerizing resin (DuraLay; Reliance Dental Mfg Co, Worth, IL) was used. Each file was rotated clockwise at a speed of 300 rpm until fracture occurred. Results: Group A (AF Blue S4) showed higher TtF and AD than Group B (S-One), and statistical analysis found significant differences between the two instruments (p<0.05). The mean values for FL showed no significant differences (p>0.05) between the two instruments. Conclusion: The AF Blue S4 seems to have a higher resistance to torsional stress in vitro. Clinically, the use of AF Blue S4 could be safer in narrow canals.

Observation of strongly entangled photon pairs from a nanowire quantum dot.

A bright photon source that combines high-fidelity entanglement, on-demand generation, high extraction efficiency, directional and coherent emission, as well as position control at the nanoscale is required for implementing ambitious schemes in quantum information processing, such as that of a quantum repeater. Still, all of these properties have not yet been achieved in a single device. Semiconductor quantum dots embedded in nanowire waveguides potentially satisfy all of these requirements; however, although theoretically predicted, entanglement has not yet been demonstrated for a nanowire quantum dot. Here, we demonstrate a bright and coherent source of strongly entangled photon pairs from a position-controlled nanowire quantum dot with a fidelity as high as 0.859±0.006 and concurrence of 0.80±0.02. The two-photon quantum state is modified via the nanowire shape. Our new nanoscale entangled photon source can be integrated at desired positions in a quantum photonic circuit, single-electron devices and light-emitting diodes.

Optimization of pre-, intra- and postoperative hyperthermic treatment in inoperable lower bowel and liver tumors.

Traditional therapies in malignant tumors are often inadequate, either because the tumors aren not responsive or because the tolerance dosage has little effect. With this in mind, our study examined advanced tumors of the lower bowel and liver. We evaluated the results of 10 cases of anorectal epidermoid cancer. We treated these patients with radiofrequency hyperthermia, since previous radiotherapy was unsuccessful. The patients had significant tumor remission, along with a 'free-of-disease' follow-up of 10 months. In this paper, we also report the positive response in 10 cases of multifocal liver tumors. All these tumors had metastasized from gastrointestinal sites and were not responsive to traditional therapies. These patients had remission with a follow-up of 6 months. In the first cases, we associated 'low-dose' radiotherapy with hyperthermia; in the latter cases, we induced chemoembolization and also associated it with hyperthermia. We emphasize these associations and suggest the very important role of intraoperative hyperthermia in absolutely inoperable cases or in those cases previously diagnosed as unresectable.